Patent publication 1 discloses a vehicle electronic control unit (hereinafter referred to as the ECU) for maintaining an operating state even when the ignition switch is inactivated by directly being supplied with power from an on-vehicle battery. The vehicle ECU includes a central processing unit (hereinafter referred to as the CPU).
In such a vehicle ECU, the CPU must undergo an initial process to check the operation of the CPU. However, in the vehicle ECU of patent publication 1, the initial process of the CPU is performed only when dismounting and mounting the on-vehicle battery. The dismounting and mounting of the on-vehicle battery is not frequently performed. Therefore, the initial process may not be performed over a long period of time if the initial process of the CPU is performed only when the on-vehicle battery is mounted or dismounted.    [Patent Publication 1]: Japanese Laid-Open Patent Publication No. 2003-70175